jpruder, the Regular TA 900 Series gateways will not support this as only one of the T1 interfaces on a TA 904 (or any TA900 Series gateway) can support a voice T1. A TA900e Series (908e with a single DSP is the smallest, least expensive build) will work using T1 0/3 and T1 0/4 as the TDM voice interfaces but this is not the intended design of the 900e so it's never been tested and approved. The ATLAS Is still ADTRANs recommended and supported solution for PRI to T1 conversion.
Hope this helps.
I went ahead and flagged the "Correct Answer" on this post to make it more visible and help other members of the community find solutions more easily.
I actually tested this on my bench and it did function as I thought it would. Yes it would still be an unsupported apllication.